1. Field of the Invention
The present invention relates to a styrenic block copolymer and a process for producing the copolymer. More particularly, it pertains to a styrenic block copolymer which has a high degree of syndiotactic configuration and capabilities of compatibility and adhesiveness; a process for efficiently producing the copolymer; a high-performance resin composition formed by compositing the copolymer and taking full advantage thereof; and a multi-layer material comprising the copolymer or the resin composition.
2. Description of Related Art
Heretofore, styrenic polymers produced by the radical polymerization method have been molded to various shapes by various molding methods and widely used as domestic electrical appliances, office machines, household goods, packaging containers, toys, furnitures, synthetic papers and other industrial materials. Because of their atactic configuration in stereochemical structure, however, such styrenic polymers have suffered the disadvantages of inferior heat resistance and chemical resistance.
In order to solve the above-mentioned disadvantages of the styrenic polymers having atactic configuration, the group of the present inventors succeeded in the development of the styrenic polymers having a high degree of syndiotactic configuration, and further a syndiotactic styrenic polymer formed by copolymerizing styrene monomer with an other monomer (refer to Japanese Patent Application Laid-Open Nos. 104818/1987 and 241009/1988).
The above-developed syndiotactic polymers and copolymers are excellent in heat resistance, chemical resistance and electrical properties, and are expected to find new applications in a variety of fields. However, the above-mentioned syndiotactic polystyrene-based polymer suffers the disadvantage that it is not sufficient in compatibility with an other type of resin and adhesivity to a different kind of material. Accordingly, a composite material of the above-mentioned syndiotactic polystyrene-based polymer and a different material involves the problem with inevitable deterioration of dynamical properties.
Under such circumstances, intensive research and investigation were made by the present inventors for the purpose of developing a styrenic polymer of syndiotactic configuration having capabilities of compatibility and adhesiveness; a high performance resin composition formed by compositing said syndiotactic polymer through the full use of the advantages thereof; and a multi-layer material comprising said syndiotactic polymer or said resin composition.
As a result, it has been found by the present inventors that the above-mentioned purpose is attained by the application of a styrenic block copolymer having a reduced viscosity within a prescribed range which comprises the segments composed of a styrenic polymer having a high degree of syndiotactic configuration and the segments composed of a specific styrenic polymer. The present invention has been accomplished on the basis of the aforestated finding and information.